The procoagulant activity (PCA) of disrupted monocytes was examined in 32 diabetic patients (26 with insulin-dependent and 6 with non-insulin-dependent diabetes) versus 30 control subjects. Diabetes monocytes exhibited a weak PCA before any incubation, associated in 10 cases with a significant amount of factor VII activity. Incubation led to a significant rise in PCA in diabetes cells, when stimulated with lipopolysaccharide or not, and in control cells only after stimulation. In incubated diabetes cells, PCA was prothrombinase-like when factor VII was associated with the freshly isolated cells, and tissue factor-like (as in the controls) when no factor VII was associated with the cells. The characteristics of PCA were not correlated with clinical features or with the type of diabetes. Our study suggests that diabetes monocytes exhibit a higher level of PCA than control ones, possibly corresponding to an in vivo stimulation, or at least a higher responsiveness to stimuli occurring in vitro.